U.S. patent application number 16/366861 was filed with the patent office on 2020-10-01 for auxiliary heat exchanger for hvac system.
The applicant listed for this patent is Johnson Controls Technology Company. Invention is credited to Anil V. Bhosale, Neelkanth S. Gupte, Ketan S. Khedkar, Nikhil N. Naik, Hambirarao S. Sawant.
Application Number | 20200309393 16/366861 |
Document ID | / |
Family ID | 1000003992557 |
Filed Date | 2020-10-01 |
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United States Patent
Application |
20200309393 |
Kind Code |
A1 |
Bhosale; Anil V. ; et
al. |
October 1, 2020 |
AUXILIARY HEAT EXCHANGER FOR HVAC SYSTEM
Abstract
A heating, ventilation, and/or air conditioning (HVAC) system,
includes a housing having a wall with an exterior surface
configured to be exposed to an ambient environment. The HVAC system
further includes a first heat exchanger disposed within the housing
and forming part of a refrigerant circuit of the HVAC system and a
second heat exchanger disposed within the housing and forming part
of the refrigerant circuit, in which the second heat exchanger
includes a coil coupled to the wall, such that the coil and the
wall are configured to transfer heat between the ambient
environment and refrigerant passing through the second heat
exchanger.
Inventors: |
Bhosale; Anil V.; (District
Satara, IN) ; Khedkar; Ketan S.; (Pune, IN) ;
Naik; Nikhil N.; (Ratnagiri, IN) ; Sawant; Hambirarao
S.; (Belgaum, IN) ; Gupte; Neelkanth S.;
(Katy, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Johnson Controls Technology Company |
Auburn Hills |
MI |
US |
|
|
Family ID: |
1000003992557 |
Appl. No.: |
16/366861 |
Filed: |
March 27, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62824078 |
Mar 26, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24F 13/20 20130101;
F24F 11/84 20180101; F24F 3/044 20130101; F24F 13/30 20130101; F24F
2221/16 20130101 |
International
Class: |
F24F 3/044 20060101
F24F003/044; F24F 11/84 20060101 F24F011/84; F24F 13/20 20060101
F24F013/20; F24F 13/30 20060101 F24F013/30 |
Claims
1. A heating, ventilation, and/or air conditioning (HVAC) system,
comprising: a housing having a wall with an exterior surface
configured to be exposed to an ambient environment; a first heat
exchanger disposed within the housing and forming part of a
refrigerant circuit of the HVAC system; and a second heat exchanger
disposed within the housing and forming part of the refrigerant
circuit, wherein the second heat exchanger includes a coil coupled
to the wall, such that the coil and the wall are configured to
transfer heat between the ambient environment and refrigerant
passing through the second heat exchanger.
2. The HVAC system of claim 1, wherein the wall includes an
interior surface within the housing and opposite the exterior
surface, and wherein the coil of the second heat exchanger is
coupled to the interior surface.
3. The HVAC system of claim 2, wherein the coil of the second heat
exchanger is coupled to the interior surface via a conductive
tape.
4. The HVAC system of claim 2, wherein the interior surface
includes grooves configured to receive the coil of the second heat
exchanger.
5. The HVAC system of claim 1, comprising insulation having a
conductive filler configured to thermally couple the second heat
exchanger with the wall, such that the conductive filler is
configured to conduct heat from the coil to the wall.
6. The HVAC system of claim 1, comprising insulation disposed
between the second heat exchanger and an interior partition of the
HVAC system, wherein the insulation is configured to restrict an
air flow within the housing from contacting the coil.
7. The HVAC system of claim 1, comprising a fan configured to
direct air flow across the first heat exchanger and away from the
second heat exchanger.
8. The HVAC system of claim 1, comprising a conduit assembly of the
refrigerant circuit, wherein the conduit assembly is configured to
direct refrigerant flow to the first heat exchanger and the second
heat exchanger in a parallel arrangement.
9. The HVAC system of claim 8, comprising a compressor disposed
along the refrigerant circuit, wherein the conduit assembly is
configured to split a total amount of refrigerant discharged from
the compressor between the first and second heat exchangers.
10. The HVAC system of claim 1, wherein the coil is directly
coupled to and in contact with an interior surface of the wall
opposite the exterior surface.
11. A heating, ventilation, and/or air conditioning (HVAC) system,
comprising: a housing having a wall with a first side exposed to an
ambient environment surrounding the housing and a second side
having insulation coupled thereto; a first heat exchanger disposed
within the housing and along a circuit, wherein the first heat
exchanger is configured to transfer heat between an air flow and a
refrigerant directed through the circuit; a second heat exchanger
disposed within the housing and along the circuit, wherein the
second heat exchanger is coupled to the insulation, and the second
heat exchanger is configured to receive the refrigerant and
transfer heat from the refrigerant to the ambient environment via
the insulation and the wall; and a conduit assembly of the circuit
coupled to the first heat exchanger and the second heat exchanger,
wherein the conduit assembly is configured to direct the
refrigerant to the first heat exchanger and the second heat
exchanger in a parallel arrangement.
12. The HVAC system of claim 11, wherein the conduit assembly
includes a valve, wherein the valve is configured to receive the
refrigerant from a compressor disposed along the circuit and direct
a first portion of the refrigerant to the first heat exchanger and
direct a second portion of the refrigerant to the second heat
exchanger.
13. The HVAC system of claim 12, comprising the compressor, wherein
the compressor is configured to pressurize the refrigerant and
discharge pressurized refrigerant toward the valve.
14. The HVAC system of claim 12, comprising a controller configured
to adjust a position of the valve to control a first amount of
refrigerant in the first portion and control a second amount of
refrigerant in the second portion based on an operating parameter
of the HVAC system.
15. The HVAC system of claim 11, comprising a fan configured to
direct air across the second heat exchanger.
16. The HVAC system of claim 11, wherein the second heat exchanger
includes a fin coupled to the insulation, wherein the fin is
configured to transfer heat from the refrigerant flowing through
the second heat exchanger to the ambient environment via the
insulation and the wall.
17. The HVAC system of claim of claim 11, wherein the second heat
exchanger is a microchannel heat exchanger or a shell and tube heat
exchanger.
18. A heating, ventilation, and/or air conditioning (HVAC) system,
comprising: a housing having a wall with an exterior surface
configured to be exposed to an ambient environment and an interior
surface configured to be exposed to an interior of the housing; a
first heat exchanger disposed within the interior of the housing; a
second heat exchanger having a coil coupled to the interior surface
of the wall to enable heat transfer between the ambient environment
and refrigerant flowing through the coil; a conduit assembly
coupled to the first heat exchanger and the second heat exchanger
and having a valve configured to direct the refrigerant to the
first heat exchanger and the second heat exchanger in a parallel
arrangement; and a controller configured to adjust a position of
the valve to control amounts of the refrigerant directed to the
first heat exchanger and the second heat exchanger.
19. The HVAC system of claim 18, wherein the valve is configured to
direct a first portion of the refrigerant from a compressor to the
first heat exchanger, and a second portion of the refrigerant from
the compressor to the second heat exchanger.
20. The HVAC system of claim 19, wherein the conduit assembly
includes an additional valve configured to receive and combine the
first portion and the second portion of the refrigerant from the
first heat exchanger and the second heat exchanger.
21. The HVAC system of claim 20, wherein the controller is
communicatively coupled to the valve and the additional valve, and
wherein the controller is configured to adjust a first position of
the valve and adjust a second position of the additional valve to
control the amounts of the refrigerant in the first portion and the
second portion based on an operating parameter of the HVAC
system.
22. The HVAC system of claim 21, wherein the operating parameter is
a temperature of the ambient environment, a temperature of the
refrigerant, a pressure of the refrigerant, a desired temperature
of a supply air flow conditioned by the HVAC system, or any
combination thereof.
23. The HVAC system of claim 18, wherein the coil is disposed in a
serpentine arrangement along the interior surface of the wall.
24. The HVAC system of claim 18, wherein the first heat exchanger
is a first condenser, the second heat exchanger is a second
condenser, and the HVAC system includes an evaporator configured to
receive the refrigerant from the first condenser and the second
condenser, and wherein the evaporator is configured to place the
refrigerant in a heat exchange relationship with a supply air flow
supplied to a space conditioned by the HVAC system.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from and the benefit of
U.S. Provisional Application Ser. No. 62/824,078, entitled
"AUXILIARY HEAT EXCHANGER FOR HVAC SYSTEM", filed Mar. 26, 2019,
which is hereby incorporated by reference.
BACKGROUND
[0002] This section is intended to introduce the reader to various
aspects of art that may be related to various aspects of the
present disclosure, which are described below. This discussion is
believed to be helpful in providing the reader with background
information to facilitate a better understanding of the various
aspects of the present disclosure. Accordingly, it should be
understood that these statements are to be read in this light, and
not as admissions of prior art.
[0003] Environmental control systems are utilized in residential,
commercial, and industrial environments to control environmental
properties, such as temperature and humidity, for occupants of the
respective environments. The environmental control system may
control the environmental properties through control of an air flow
delivered to the environment. For example, a heating, ventilation,
and air conditioning (HVAC) system may circulate a refrigerant and
place the refrigerant in a heat exchange relationship with an air
flow to condition the air flow. In some cases, the HVAC system may
include a heat exchanger configured to remove heat from the
refrigerant. However, a capacity of the heat exchanger to remove
the heat from the refrigerant may be limited.
SUMMARY
[0004] A summary of certain embodiments disclosed herein is set
forth below. It should be understood that these aspects are
presented merely to provide the reader with a brief summary of
these certain embodiments and that these aspects are not intended
to limit the scope of this disclosure. Indeed, this disclosure may
encompass a variety of aspects that may not be set forth below.
[0005] In one embodiment, a heating, ventilation, and/or air
conditioning (HVAC) system, includes a housing having a wall with
an exterior surface configured to be exposed to an ambient
environment. The HVAC system further includes a first heat
exchanger disposed within the housing and forming part of a
refrigerant circuit of the HVAC system and a second heat exchanger
disposed within the housing and forming part of the refrigerant
circuit, in which the second heat exchanger includes a coil coupled
to the wall, such that the coil and the wall are configured to
transfer heat between the ambient environment and refrigerant
passing through the second heat exchanger.
[0006] In another embodiment, a heating, ventilation, and/or air
conditioning (HVAC) system includes a housing having a wall with a
first side exposed to an ambient environment surrounding the
housing and a second side having insulation coupled thereto. The
HVAC system also includes a first heat exchanger disposed within
the housing and along a circuit, in which the first heat exchanger
is configured to transfer heat between an air flow and a
refrigerant directed through the circuit, and a second heat
exchanger disposed within the housing and along the circuit, in
which the second heat exchanger is coupled to the insulation, and
the second heat exchanger is configured to receive the refrigerant
and transfer heat from the refrigerant to the ambient environment
via the insulation and the wall. The HVAC system further includes a
conduit assembly of the circuit coupled to the first heat exchanger
and the second heat exchanger, in which the conduit assembly is
configured to direct the refrigerant to the first heat exchanger
and the second heat exchanger in a parallel arrangement.
[0007] In another embodiment, a heating, ventilation, and/or air
conditioning (HVAC) system includes a housing having a wall with an
exterior surface configured to be exposed to an ambient environment
and an interior surface configured to be exposed to an interior of
the housing, a first heat exchanger disposed within the interior of
the housing, and a second heat exchanger having a coil coupled to
the interior surface of the wall to enable heat transfer between
the ambient environment and refrigerant flowing through the coil.
The HVAC system further includes a conduit assembly coupled to the
first heat exchanger and the second heat exchanger and having a
valve configured to direct the refrigerant to the first heat
exchanger and the second heat exchanger in a parallel arrangement,
and a controller configured to adjust a position of the valve to
control amounts of the refrigerant directed to the first heat
exchanger and the second heat exchanger.
DRAWINGS
[0008] Various aspects of this disclosure may be better understood
upon reading the following detailed description and upon reference
to the drawings in which:
[0009] FIG. 1 is a perspective view of an embodiment of a heating,
ventilation, and/or air conditioning (HVAC) system for
environmental management that may employ one or more HVAC units, in
accordance with an aspect of the present disclosure;
[0010] FIG. 2 is a perspective view of an embodiment of a packaged
HVAC unit that may be used in the HVAC system of FIG. 1, in
accordance with an aspect of the present disclosure;
[0011] FIG. 3 is a cutaway perspective view of an embodiment of a
residential, split HVAC system, in accordance with an aspect of the
present disclosure;
[0012] FIG. 4 is a schematic of an embodiment of a vapor
compression system that can be used in any of the systems of FIGS.
1-3, in accordance with an aspect of the present disclosure;
[0013] FIG. 5 is a schematic of an HVAC system having an auxiliary
heat exchanger, in accordance with an aspect of the present
disclosure;
[0014] FIG. 6 is a cutaway perspective view of an embodiment of the
HVAC system of FIG. 5 having a condenser and the auxiliary
condenser, where the HVAC system is configured to be disposed
exterior to a building conditioned by the HVAC system, in
accordance with an aspect of the present disclosure;
[0015] FIG. 7 is a schematic of an embodiment of an auxiliary
condenser coupled to a wall of an HVAC system, in accordance with
an aspect of the present disclosure;
[0016] FIG. 8 is a schematic cross-sectional view of an embodiment
of a coil of the auxiliary condenser coupled to the wall, in
accordance with an aspect of the present disclosure;
[0017] FIG. 9 is a schematic cross-sectional view of an embodiment
of an auxiliary heat exchanger positioned adjacent to a wall of an
HVAC system, in accordance with an aspect of the present
disclosure; and
[0018] FIG. 10 is a schematic of an embodiment of an auxiliary
condenser having a fan configured to direct air across the
auxiliary condenser, in accordance with an aspect of the present
disclosure.
DETAILED DESCRIPTION
[0019] One or more specific embodiments will be described below. In
an effort to provide a concise description of these embodiments,
not all features of an actual implementation are described in the
specification. It should be appreciated that in the development of
any such actual implementation, as in any engineering or design
project, numerous implementation-specific decisions must be made to
achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which may vary
from one implementation to another. Moreover, it should be
appreciated that such a development effort might be complex and
time consuming, but would nevertheless be a routine undertaking of
design, fabrication, and manufacture for those of ordinary skill
having the benefit of this disclosure.
[0020] When introducing elements of various embodiments of the
present disclosure, the articles "a," "an," and "the" are intended
to mean that there are one or more of the elements. The terms
"comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements. Additionally, it should be understood that
references to "one embodiment" or "an embodiment" of the present
disclosure are not intended to be interpreted as excluding the
existence of additional embodiments that also incorporate the
recited features.
[0021] The present disclosure is directed to a heating,
ventilation, and/or air conditioning (HVAC) system that includes a
refrigerant circuit configured to circulate a refrigerant in order
to condition an environment, such as a building or a home. For
example, the refrigerant may be pressurized by a compressor of the
refrigerant circuit and may be directed toward a condenser of the
refrigerant circuit, where the pressurized refrigerant is cooled
and condensed. The cooled refrigerant may then be directed to an
evaporator of the refrigerant circuit to be placed in a heat
exchange relationship with a supply air flow. Heat exchange between
the supply air flow and the refrigerant within the evaporator
causes the supply air flow to cool before the supply air flow is
delivered to the environment conditioned by the HVAC system.
[0022] In some embodiments, the HVAC system utilizes a fan
configured to direct or draw air across the condenser to remove
heat from the refrigerant within the condenser. A speed of the fan
may be controlled based on a desired amount of cooling of the
refrigerant in the condenser. For example, the fan speed may be
increased to increase the amount of cooling of the refrigerant.
However, increasing the fan speed also increases energy consumption
of the HVAC system, and thus, the capacity of the condenser to cool
the refrigerant may be limited by the operation of the fan as well
as energy consumption limits.
[0023] Accordingly, embodiments of the present disclosure are
directed to an auxiliary heat exchanger that may be included in the
HVAC system to increase a capacity for cooling the refrigerant. For
example, a portion of the refrigerant in the refrigerant circuit
may be directed to the auxiliary heat exchanger, which may reduce
an amount of refrigerant directed to a primary heat exchanger, such
as the condenser utilizing the fan. In certain embodiments, the
auxiliary heat exchanger may place the refrigerant in a heat
exchange relationship with ambient air to cool the refrigerant
without using mechanical circulation devices, such as fans, to
facilitate cooling, which may reduce an amount of energy
consumption by the HVAC system. In other embodiments, the auxiliary
heat exchanger may utilize an auxiliary fan to increase a cooling
capacity of the auxiliary heat exchanger. In any case, a speed of
the fan may be reduced as a result of the reduction in refrigerant
flowing through the primary heat exchanger, such as the condenser.
As such, the auxiliary heat exchanger may increase an efficiency of
the HVAC system.
[0024] Turning now to the drawings, FIG. 1 illustrates an
embodiment of a heating, ventilation, and/or air conditioning
(HVAC) system for environmental management that may employ one or
more HVAC units. As used herein, an HVAC system includes any number
of components configured to enable regulation of parameters related
to climate characteristics, such as temperature, humidity, air
flow, pressure, air quality, and so forth. For example, an "HVAC
system" as used herein is defined as conventionally understood and
as further described herein. Components or parts of an "HVAC
system" may include, but are not limited to, all, some of, or
individual parts such as a heat exchanger, a heater, an air flow
control device, such as a fan, a sensor configured to detect a
climate characteristic or operating parameter, a filter, a control
device configured to regulate operation of an HVAC system
component, a component configured to enable regulation of climate
characteristics, or a combination thereof. An "HVAC system" is a
system configured to provide such functions as heating, cooling,
ventilation, dehumidification, pressurization, refrigeration,
filtration, or any combination thereof. The embodiments described
herein may be utilized in a variety of applications to control
climate characteristics, such as residential, commercial,
industrial, transportation, or other applications where climate
control is desired.
[0025] In the illustrated embodiment, a building 10 is air
conditioned by a system that includes an HVAC unit 12. The building
10 may be a commercial structure or a residential structure. As
shown, the HVAC unit 12 is disposed on the roof of the building 10;
however, the HVAC unit 12 may be located in other equipment rooms
or areas adjacent the building 10. The HVAC unit 12 may be a single
package unit containing other equipment, such as a blower,
integrated air handler, and/or auxiliary heating unit. In other
embodiments, the HVAC unit 12 may be part of a split HVAC system,
such as the system shown in FIG. 3, which includes an outdoor HVAC
unit 58 and an indoor HVAC unit 56.
[0026] The HVAC unit 12 is an air cooled device that implements a
refrigeration cycle to provide conditioned air to the building 10.
Specifically, the HVAC unit 12 may include one or more heat
exchangers across which an air flow is passed to condition the air
flow before the air flow is supplied to the building. In the
illustrated embodiment, the HVAC unit 12 is a rooftop unit (RTU)
that conditions a supply air stream, such as environmental air
and/or a return air flow from the building 10. After the HVAC unit
12 conditions the air, the air is supplied to the building 10 via
ductwork 14 extending throughout the building 10 from the HVAC unit
12. For example, the ductwork 14 may extend to various individual
floors or other sections of the building 10. In certain
embodiments, the HVAC unit 12 may be a heat pump that provides both
heating and cooling to the building with one refrigeration circuit
configured to operate in different modes. In other embodiments, the
HVAC unit 12 may include one or more refrigeration circuits for
cooling an air stream and a furnace for heating the air stream.
[0027] A control device 16, one type of which may be a thermostat,
may be used to designate the temperature of the conditioned air.
The control device 16 also may be used to control the flow of air
through the ductwork 14. For example, the control device 16 may be
used to regulate operation of one or more components of the HVAC
unit 12 or other components, such as dampers and fans, within the
building 10 that may control flow of air through and/or from the
ductwork 14. In some embodiments, other devices may be included in
the system, such as pressure and/or temperature transducers or
switches that sense the temperatures and pressures of the supply
air, return air, and so forth. Moreover, the control device 16 may
include computer systems that are integrated with or separate from
other building control or monitoring systems, and even systems that
are remote from the building 10.
[0028] FIG. 2 is a perspective view of an embodiment of the HVAC
unit 12. In the illustrated embodiment, the HVAC unit 12 is a
single package unit that may include one or more independent
refrigeration circuits and components that are tested, charged,
wired, piped, and ready for installation. The HVAC unit 12 may
provide a variety of heating and/or cooling functions, such as
cooling only, heating only, cooling with electric heat, cooling
with dehumidification, cooling with gas heat, or cooling with a
heat pump. As described above, the HVAC unit 12 may directly cool
and/or heat an air stream provided to the building 10 to condition
a space in the building 10.
[0029] As shown in the illustrated embodiment of FIG. 2, a cabinet
24 encloses the HVAC unit 12 and provides structural support and
protection to the internal components from environmental and other
contaminants. In some embodiments, the cabinet 24 may be
constructed of galvanized steel and insulated with aluminum foil
faced insulation. Rails 26 may be joined to the bottom perimeter of
the cabinet 24 and provide a foundation for the HVAC unit 12. In
certain embodiments, the rails 26 may provide access for a forklift
and/or overhead rigging to facilitate installation and/or removal
of the HVAC unit 12. In some embodiments, the rails 26 may fit into
"curbs" on the roof to enable the HVAC unit 12 to provide air to
the ductwork 14 from the bottom of the HVAC unit 12 while blocking
elements such as rain from leaking into the building 10.
[0030] The HVAC unit 12 includes heat exchangers 28 and 30 in fluid
communication with one or more refrigeration circuits. Tubes within
the heat exchangers 28 and 30 may circulate refrigerant, such as
R-410A, through the heat exchangers 28 and 30. The tubes may be of
various types, such as multichannel tubes, conventional copper or
aluminum tubing, and so forth. Together, the heat exchangers 28 and
30 may implement a thermal cycle in which the refrigerant undergoes
phase changes and/or temperature changes as it flows through the
heat exchangers 28 and 30 to produce heated and/or cooled air. For
example, the heat exchanger 28 may function as a condenser where
heat is released from the refrigerant to ambient air, and the heat
exchanger 30 may function as an evaporator where the refrigerant
absorbs heat to cool an air stream. In other embodiments, the HVAC
unit 12 may operate in a heat pump mode where the roles of the heat
exchangers 28 and 30 may be reversed. That is, the heat exchanger
28 may function as an evaporator and the heat exchanger 30 may
function as a condenser. In further embodiments, the HVAC unit 12
may include a furnace for heating the air stream that is supplied
to the building 10. While the illustrated embodiment of FIG. 2
shows the HVAC unit 12 having two of the heat exchangers 28 and 30,
in other embodiments, the HVAC unit 12 may include one heat
exchanger or more than two heat exchangers.
[0031] The heat exchanger 30 is located within a compartment 31
that separates the heat exchanger 30 from the heat exchanger 28.
Fans 32 draw air from the environment through the heat exchanger
28. Air may be heated and/or cooled as the air flows through the
heat exchanger 28 before being released back to the environment
surrounding the HVAC unit 12. A blower assembly 34, powered by a
motor 36, draws air through the heat exchanger 30 to heat or cool
the air. The heated or cooled air may be directed to the building
10 by the ductwork 14, which may be connected to the HVAC unit 12.
Before flowing through the heat exchanger 30, the conditioned air
flows through one or more filters 38 that may remove particulates
and contaminants from the air. In certain embodiments, the filters
38 may be disposed on the air intake side of the heat exchanger 30
to prevent contaminants from contacting the heat exchanger 30.
[0032] The HVAC unit 12 also may include other equipment for
implementing the thermal cycle. Compressors 42 increase the
pressure and temperature of the refrigerant before the refrigerant
enters the heat exchanger 28. The compressors 42 may be any
suitable type of compressors, such as scroll compressors, rotary
compressors, screw compressors, or reciprocating compressors. In
some embodiments, the compressors 42 may include a pair of hermetic
direct drive compressors arranged in a dual stage configuration 44.
However, in other embodiments, any number of the compressors 42 may
be provided to achieve various stages of heating and/or cooling. As
may be appreciated, additional equipment and devices may be
included in the HVAC unit 12, such as a solid-core filter drier, a
drain pan, a disconnect switch, an economizer, pressure switches,
phase monitors, and humidity sensors, among other things.
[0033] The HVAC unit 12 may receive power through a terminal block
46. For example, a high voltage power source may be connected to
the terminal block 46 to power the equipment. The operation of the
HVAC unit 12 may be governed or regulated by a control board 48.
The control board 48 may include control circuitry connected to a
thermostat, sensors, and alarms. One or more of these components
may be referred to herein separately or collectively as the control
device 16. The control circuitry may be configured to control
operation of the equipment, provide alarms, and monitor safety
switches. Wiring 49 may connect the control board 48 and the
terminal block 46 to the equipment of the HVAC unit 12.
[0034] FIG. 3 illustrates a residential heating and cooling system
50, also in accordance with present techniques. The residential
heating and cooling system 50 may provide heated and cooled air to
a residential structure, as well as provide outside air for
ventilation and provide improved indoor air quality (IAQ) through
devices such as ultraviolet lights and air filters. In the
illustrated embodiment, the residential heating and cooling system
50 is a split HVAC system. In general, a residence 52 conditioned
by a split HVAC system may include refrigerant conduits 54 that
operatively couple the indoor unit 56 to the outdoor unit 58. The
indoor unit 56 may be positioned in a utility room, an attic, a
basement, and so forth. The outdoor unit 58 is typically situated
adjacent to a side of residence 52 and is covered by a shroud to
protect the system components and to prevent leaves and other
debris or contaminants from entering the unit. The refrigerant
conduits 54 transfer refrigerant between the indoor unit 56 and the
outdoor unit 58, typically transferring primarily liquid
refrigerant in one direction and primarily vaporized refrigerant in
an opposite direction.
[0035] When the system shown in FIG. 3 is operating as an air
conditioner, a heat exchanger 60 in the outdoor unit 58 serves as a
condenser for re-condensing vaporized refrigerant flowing from the
indoor unit 56 to the outdoor unit 58 via one of the refrigerant
conduits 54. In these applications, a heat exchanger 62 of the
indoor unit functions as an evaporator. Specifically, the heat
exchanger 62 receives liquid refrigerant, which may be expanded by
an expansion device, and evaporates the refrigerant before
returning it to the outdoor unit 58.
[0036] The outdoor unit 58 draws environmental air through the heat
exchanger 60 using a fan 64 and expels the air above the outdoor
unit 58. When operating as an air conditioner, the air is heated by
the heat exchanger 60 within the outdoor unit 58 and exits the unit
at a temperature higher than it entered. The indoor unit 56
includes a blower or fan 66 that directs air through or across the
indoor heat exchanger 62, where the air is cooled when the system
is operating in air conditioning mode. Thereafter, the air is
passed through ductwork 68 that directs the air to the residence
52. The overall system operates to maintain a desired temperature
as set by a system controller. When the temperature sensed inside
the residence 52 is higher than the set point on the thermostat, or
the set point plus a small amount, the residential heating and
cooling system 50 may become operative to refrigerate additional
air for circulation through the residence 52. When the temperature
reaches the set point, or the set point minus a small amount, the
residential heating and cooling system 50 may stop the
refrigeration cycle temporarily.
[0037] The residential heating and cooling system 50 may also
operate as a heat pump. When operating as a heat pump, the roles of
heat exchangers 60 and 62 are reversed. That is, the heat exchanger
60 of the outdoor unit 58 will serve as an evaporator to evaporate
refrigerant and thereby cool air entering the outdoor unit 58 as
the air passes over the outdoor heat exchanger 60. The indoor heat
exchanger 62 will receive a stream of air blown over it and will
heat the air by condensing the refrigerant.
[0038] In some embodiments, the indoor unit 56 may include a
furnace system 70. For example, the indoor unit 56 may include the
furnace system 70 when the residential heating and cooling system
50 is not configured to operate as a heat pump. The furnace system
70 may include a burner assembly and heat exchanger, among other
components, inside the indoor unit 56. Fuel is provided to the
burner assembly of the furnace 70 where it is mixed with air and
combusted to form combustion products. The combustion products may
pass through tubes or piping in a heat exchanger, separate from
heat exchanger 62, such that air directed by the blower 66 passes
over the tubes or pipes and extracts heat from the combustion
products. The heated air may then be routed from the furnace system
70 to the ductwork 68 for heating the residence 52.
[0039] FIG. 4 is an embodiment of a vapor compression system 72
that can be used in any of the systems described above. The vapor
compression system 72 may circulate a refrigerant through a circuit
starting with a compressor 74. The circuit may also include a
condenser 76, an expansion valve(s) or device(s) 78, and an
evaporator 80. The vapor compression system 72 may further include
a control panel 82 that has an analog to digital (A/D) converter
84, a microprocessor 86, a non-volatile memory 88, and/or an
interface board 90. The control panel 82 and its components may
function to regulate operation of the vapor compression system 72
based on feedback from an operator, from sensors of the vapor
compression system 72 that detect operating conditions, and so
forth.
[0040] In some embodiments, the vapor compression system 72 may use
one or more of a variable speed drive (VSDs) 92, a motor 94, the
compressor 74, the condenser 76, the expansion valve or device 78,
and/or the evaporator 80. The motor 94 may drive the compressor 74
and may be powered by the variable speed drive (VSD) 92. The VSD 92
receives alternating current (AC) power having a particular fixed
line voltage and fixed line frequency from an AC power source, and
provides power having a variable voltage and frequency to the motor
94. In other embodiments, the motor 94 may be powered directly from
an AC or direct current (DC) power source. The motor 94 may include
any type of electric motor that can be powered by a VSD or directly
from an AC or DC power source, such as a switched reluctance motor,
an induction motor, an electronically commutated permanent magnet
motor, or another suitable motor.
[0041] The compressor 74 compresses a refrigerant vapor and
delivers the vapor to the condenser 76 through a discharge passage.
In some embodiments, the compressor 74 may be a centrifugal
compressor. The refrigerant vapor delivered by the compressor 74 to
the condenser 76 may transfer heat to a fluid passing across the
condenser 76, such as ambient or environmental air 96. The
refrigerant vapor may condense to a refrigerant liquid in the
condenser 76 as a result of thermal heat transfer with the
environmental air 96. The liquid refrigerant from the condenser 76
may flow through the expansion device 78 to the evaporator 80.
[0042] The liquid refrigerant delivered to the evaporator 80 may
absorb heat from another air stream, such as a supply air stream 98
provided to the building 10 or the residence 52. For example, the
supply air stream 98 may include ambient or environmental air,
return air from a building, or a combination of the two. The liquid
refrigerant in the evaporator 80 may undergo a phase change from
the liquid refrigerant to a refrigerant vapor. In this manner, the
evaporator 80 may reduce the temperature of the supply air stream
98 via thermal heat transfer with the refrigerant. Thereafter, the
vapor refrigerant exits the evaporator 80 and returns to the
compressor 74 by a suction line to complete the cycle.
[0043] In some embodiments, the vapor compression system 72 may
further include a reheat coil in addition to the evaporator 80. For
example, the reheat coil may be positioned downstream of the
evaporator relative to the supply air stream 98 and may reheat the
supply air stream 98 when the supply air stream 98 is overcooled to
remove humidity from the supply air stream 98 before the supply air
stream 98 is directed to the building 10 or the residence 52.
[0044] It should be appreciated that any of the features described
herein may be incorporated with the HVAC unit 12, the residential
heating and cooling system 50, or other HVAC systems. Additionally,
while the features disclosed herein are described in the context of
embodiments that directly heat and cool a supply air stream
provided to a building or other load, embodiments of the present
disclosure may be applicable to other HVAC systems as well. For
example, the features described herein may be applied to mechanical
cooling systems, free cooling systems, chiller systems, or other
heat pump or refrigeration applications.
[0045] As discussed above, an HVAC system, such as the HVAC unit 12
and/or the residential heating and cooling system 50, may include a
refrigerant circuit configured to circulate a refrigerant through
various components in order to condition an environment or space.
In accordance with present techniques, the HVAC system may include
an auxiliary heat exchanger configured to place the refrigerant in
a heat exchange relationship with ambient air. For example, the
HVAC system may have a housing that encloses various components of
the HVAC system, and the auxiliary heat exchanger may be coupled to
the housing, such that heat may be transferred from the refrigerant
to the housing via conduction and then transferred to ambient air
via convection. Thus, the refrigerant may be cooled in the
auxiliary heat exchanger without operating additional mechanical
components, such as fans, that may increase energy consumption of
the HVAC system. The auxiliary heat exchanger may be configured to
be retrofit onto existing HVAC systems. That is, the auxiliary heat
exchanger may be readily installed within a housing of an existing
HVAC system, such that the refrigerant of the HVAC system may be
directed to the auxiliary heat exchanger in order to increase the
capacity for cooling the refrigerant. As used herein, the auxiliary
heat exchanger is implemented as a condenser configured to remove
heat from the refrigerant. However, in additional or alternative
embodiments, the auxiliary heat exchanger may be implemented as an
evaporator configured to add heat to the refrigerant, such as in a
heat pump system configured to heat the supply air flow.
Furthermore, although this disclosure primarily discusses
implementing the auxiliary heat exchanger in a rooftop unit, in
alternative embodiments, the auxiliary heat exchanger may be
implemented in other types of HVAC systems, such as with a
condenser in a split HVAC system.
[0046] FIG. 5 is a schematic view of an HVAC system 150 that may
include a refrigerant circuit 152 configured to circulate a
refrigerant therethrough. The refrigerant circuit 152 may include
an evaporator 154 configured to place the refrigerant in a heat
exchange relationship or in thermal communication with an air flow
to condition the air flow. For example, the refrigerant may absorb
thermal energy from the air flow to cool the air flow and heat the
refrigerant. The refrigerant circuit 152 may also include a
compressor 156 configured to pressurize the heated refrigerant and
direct the heated refrigerant to a first condenser 158 forming part
of the refrigerant circuit 152. The first condenser 158 is
configured to remove thermal energy from and cool the heated
refrigerant. For example, the HVAC system 150 may include a fan 160
configured to force or draw air across the first condenser 158 to
remove thermal energy from the refrigerant. In some embodiments,
the condenser 158 may include a plurality of tubes, conduits,
and/or channels through which the refrigerant flows. The fan 160
may direct air across the plurality of tubes, conduits, and/or
channels to remove thermal energy from the refrigerant directed
through the condenser 158. Additionally, the HVAC system 150
includes a second condenser 162, such as an auxiliary condenser,
forming a portion of the refrigerant circuit 152 and configured to
receive and cool the refrigerant from the compressor 156. The
second condenser 162 may expose the refrigerant to ambient air in
order to transfer heat between the refrigerant and ambient air
without operating another fan or other component to cool the
refrigerant. In certain implementations, the refrigerant circuit
152 may further include an expansion device 164, such as the
expansion device 78, configured to receive the refrigerant from the
first condenser 158 and/or second condenser 162 and to reduce a
pressure of the refrigerant. The reduction of pressure may further
cool the refrigerant to place the refrigerant in condition to
remove heat from the air flow at the evaporator 154.
[0047] In some embodiments, the second condenser 162 may be coupled
to or otherwise positioned on a portion of the HVAC system 150 that
is exposed to ambient air. For example, the HVAC system 150 may
include a housing, in which at least a portion of a wall of the
housing is exposed to ambient air. Thus, the second condenser 162
may be coupled to the wall of the housing in order to transfer heat
with the wall exposed to ambient air. The pressure drop of
refrigerant across the second condenser 162 may be less than the
pressure drop of refrigerant across the first condenser 158 because
less energy may be used to direct the refrigerant through the
second condenser 162 as compared to the energy used to direct the
refrigerant through the first condenser 158. In this manner, the
additional energy consumption used to direct the refrigerant
through the second condenser 162 may be relatively small, and thus,
the inclusion of the second condenser 162 in the HVAC system 150
may not substantially increase overall energy consumption of the
HVAC system 150.
[0048] Additionally, the HVAC system 150 may include a barrier 166
configured to block air directed by the fan 160 from flowing across
or along the second condenser 162. As such, the fan 160 does not
directly cause air to flow across or along the second condenser
162. Furthermore, the barrier 166 may thermally insulate the second
condenser 162 from a remainder of the HVAC system 150, such as from
the first condenser 158. Thus, heat may not transfer between the
second condenser 162 and the remainder of the HVAC system 150. In
certain embodiments, the barrier 166 may be adjustable, such as via
adjustable louvers. That is, the barrier 166 may be adjusted
between a closed position to block air from being directed across
the second condenser 162 via the fan 160, a fully open position to
enable air to be directed across the second condenser 162 via the
fan 160, or a position between the closed position and the fully
open position to enable a target amount of air to be directed
across the second condenser 162 via the fan 160.
[0049] The refrigerant circuit 152 may also include a first conduit
assembly 165, which includes components, such as conduits, tubing,
flow paths, valves, and so forth, to direct the refrigerant from
the compressor 156 to the first and second condensers 158, 162. In
some embodiments, the first conduit assembly 165 may be configured
to direct the refrigerant through the first condenser 158 and the
second condenser 162 in a parallel arrangement. In other words, the
first conduit assembly 165 may direct a first portion of the
refrigerant from the compressor 156 directly to the first condenser
158 and a second portion of the refrigerant from the compressor 156
directly to the second condenser 162, such that the first portion
of the refrigerant does not flow through the second condenser 162,
and the second portion of the refrigerant does not flow through the
first condenser 158. For example, the first conduit assembly 165
may include a first valve 168 configured to split a total amount of
refrigerant discharged from the compressor 156 between the first
and second condensers 158, 162. The first valve 168 may be
configured direct the first portion of refrigerant discharged from
the compressor 156 to the first condenser 158 and the second
portion of refrigerant discharged from the compressor 156 to the
second condenser 162.
[0050] The refrigerant circuit 152 may also include a second
conduit assembly 167 configured to direct refrigerant from the
first and second condensers 158, 162 to a second valve 170. The
second valve 170 is configured to receive and combine the first
portion of the refrigerant from the first condenser 158 and the
second portion of the refrigerant from the second condenser 162.
The second valve 170 may direct the combined first and second
portions of the refrigerant to the expansion device 164. In
additional or alternative embodiments, the first conduit assembly
165 may be configured to direct refrigerant from the compressor 156
to the first condenser 158 and the second condenser 162 in a series
arrangement. That is, the first conduit assembly 165 may direct
refrigerant from the compressor 156 to the first condenser 158 and
then to the second condenser 162 in a sequential order.
[0051] The HVAC system 150 may include a controller 172, such as
the control board 47 and/or the control panel 82, configured to
control operation of the HVAC system 150. The controller 172 may
include a memory 174 and a processor 176. The memory 174 may be a
mass storage device, a flash memory device, removable memory, or
any other non-transitory computer-readable medium that includes
instructions for the processor 176 to execute. The memory 174 may
also include volatile memory such as randomly accessible memory
(RAM) and/or non-volatile memory such as hard disc memory, flash
memory, and/or other suitable memory formats. The processor 176 may
execute the instructions stored in the memory 174.
[0052] For example, the controller 172 may be communicatively
coupled to the first valve 168 and/or the second valve 170 to
adjust the amounts of refrigerant directed to the first condenser
158 and the second condenser 162. Generally, an increased amount of
refrigerant directed through either of the condensers 158, 162
indicates an increased cooling load, or an increased amount of
cooling of the refrigerant, performed by that condenser 158, 162.
In some embodiments, the controller 172 may adjust a position of
the first valve 168 to increase or decrease the ratio between the
first portion and the second portion of refrigerant based on an
operating parameter of the HVAC system 150 determined by a sensor
178. That is, for example, the first valve 168 may be adjusted such
that a greater amount of refrigerant is directed through the second
condenser 162 relative to an amount of refrigerant directed through
the first condenser 158, or vice versa.
[0053] For instance, the operating parameter determined by the
sensor 178 may include a temperature of the ambient air, a
temperature of the refrigerant, a pressure of the refrigerant, a
desired temperature of the supply air flow, another suitable
operating parameter of the HVAC system 150, or any combination
thereof. As an example, the first valve 168 may direct a greater
amount of refrigerant through the second condenser 162 upon
determining that the temperature of the ambient air is below a
threshold value. As such, the refrigerant may be placed in thermal
communication with ambient air having a relatively low temperature
via the second condenser 162, which may remove a target amount of
heat with less energy consumption as compared to removing heat from
the refrigerant in the first condenser 158 via the fan 160. In one
example, the second condenser 162 may have a cooling load of
approximately 3 percent of a total cooling load of a 40 ton HVAC
system when the temperature of the ambient air is at 35 degrees
Celsius, and the second condenser 162 may have a cooling load of
approximately 30 percent of the total cooling load of the 40 ton
HVAC system when the temperature of the ambient air is at 18
degrees Celsius. In another example, the second condenser 162 may
have a cooling load of approximately 8 percent of a total cooling
load of a 3 ton HVAC system when the temperature of the ambient air
is at 35 degrees Celsius, and the second condenser 162 may have a
cooling load of approximately 80 percent of the total cooling load
of the 3 ton HVAC system when the temperature of the ambient air is
at 18 degrees Celsius.
[0054] In certain embodiments, the controller 172 may adjust the
speed of the fan 160 based on an amount of refrigerant directed
through the first condenser 158. For example, if the amount of
refrigerant directed through the first condenser 158 decreases,
such that the cooling load of the first condenser 158 decreases, an
operating speed of the fan 160 may also be decreased by the
controller 172 to reduce energy consumption associated with
operating the fan 160.
[0055] The controller 172 may also be configured to adjust a
position of the first valve 168 and/or the second valve 170 to
block refrigerant flow through one of the condensers 158, 162. By
way of example, the controller 172 may adjust the position of the
first valve 168 to block the first portion of refrigerant from
flowing from the compressor 156 to the first condenser 158 in
response to the sensor 178 determining the temperature of ambient
air is below a certain temperature, such as a temperature value
between 0 degrees Celsius and 10 degrees Celsius. That is, the HVAC
system 150 may be able to achieve a desired amount of cooling of
the refrigerant by directing the refrigerant through the second
condenser 162 and not the first condenser 158. In such
circumstances, operation of the fan 160 may be disabled or
suspended to reduce energy consumption, and the position of the
second valve 170 may be adjusted to enable the refrigerant to flow
from the second condenser 162 to the expansion valve 164 and block
the refrigerant from flowing from the second condenser 162 to the
first condenser 158.
[0056] The controller 172 may also adjust the position of the first
valve 168 to block the second portion of refrigerant from flowing
from the compressor 156 to the second condenser 162 in response to
the sensor 178 determining the temperature of ambient air exceeds a
threshold temperature, such as a temperature value between 30
degrees Celsius and 40 degrees Celsius. In other words, if the
temperature of ambient air is too high, the refrigerant may not be
sufficiently cooled by exchanging heat with the ambient air, and
thus, the refrigerant may be blocked from flowing through the
second condenser 162. Additionally, in such circumstances, the
controller 172 may also adjust the position of the second valve 170
to direct refrigerant from the first condenser 158 to the expansion
device 164 and block refrigerant flow from the first condenser 158
to the second condenser 162.
[0057] In some embodiments, the controller 172 may adjust the
positions of the first and second valves 168, 170 to direct
refrigerant based on a condition of the HVAC system 150. For
example, frost may accumulate at a particular location, such as an
exterior surface, of the HVAC system 150, which may impact a
performance of the HVAC system 150. In response to determining that
frost is accumulating on or in the HVAC system 150, the controller
172 may adjust a position of the first and/or second valves 168,
170 to direct heated refrigerant, such as refrigerant discharged by
the compressor 156, to defrost such sections. For instance, the
second condenser 162 may be located proximate to the exterior
surface of the HVAC system 150 housing, and the controller 172 may
adjust the position of the first and/or second valves 168, 170 to
increase the amount of refrigerant directed to the second condenser
162 to defrost the exterior surface.
[0058] Although FIG. 5 illustrates a configuration of the HVAC
system 150 having the first valve 168 and the second valve 170, in
additional or alternative embodiments, the refrigerant circuit 152
may include other valve configurations to adjust an amount of
refrigerant flow through the first condenser 158 and the second
condenser 162. For example, the refrigerant circuit 152 may include
a first valve configured to adjust an amount of refrigerant
directed from the compressor 156 to the first condenser 158, a
second valve configured to adjust an amount of refrigerant directed
from the compressor 156 to the second condenser 158, a third valve
configured to adjust an amount of refrigerant directed from the
first condenser 158 to the expansion device 164, and/or a fourth
valve configured to adjust an amount of refrigerant directed from
the second condenser 162 to the expansion device 164.
[0059] FIG. 6 is a cutaway perspective view of an embodiment of the
HVAC system 150 having the first condenser 158 and the second
condenser 162, where the HVAC system 150 is configured to be
disposed external to a building conditioned by the HVAC system 150.
For example, the HVAC system 150 may be a packaged unit and/or an
RTU, such as the HVAC unit 12 of FIGS. 1 and 2. The HVAC system 150
may include a housing 200, which encloses the evaporator 154, the
compressor 156, the first condenser 158, and/or the second
condenser 162. Furthermore, the second condenser 162 may be
configured to be coupled to an interior surface of a wall or panel
of the housing 200, whereby an exterior surface of the wall may be
exposed to an ambient environment. In some embodiments, the second
condenser 162 may be coupled to a top panel 202 of the housing 200,
which may be positioned above the evaporator 154 and the compressor
156 with respect to a vertical axis 204. As an example, the top
panel 202 may include a rectangular shape having a first length 206
that may be between 200 centimeters (cm) and 300 cm and a second
length 208 that may be between 800 cm and 900 cm. In additional or
alternative embodiments, the second condenser 162 may be coupled to
a side panel 210 of the housing 200, which may be positioned
adjacent to the evaporator 154 and the compressor 156 with respect
to a lateral axis 212. The side panel 210 may also have a
rectangular shape having the second length 208 and having a third
length 214 that may each be between 100 cm and 200 cm. In further
embodiments, the second condenser 162 may be coupled to another
wall of the housing 200, such as a wall surrounding and/or
enclosing the first condenser 158.
[0060] As illustrated in FIG. 6, the first condenser 158 is
positioned adjacent to the evaporator 154, the compressor 156, and
the second condenser 162 with respect to a longitudinal axis 216.
As such, the first portion of the refrigerant discharged by the
compressor 156 may be directed along the longitudinal axis 216 to
the first condenser 158, and the second portion of the refrigerant
discharged by the compressor 156 may be directed along the vertical
axis 204 and/or the lateral axis 212 to the second condenser 162.
Furthermore, the first condenser 158 includes a plurality of fans
160 positioned above condenser coils 218 of the first condenser 158
with respect to the vertical axis 204. The plurality of fans 160
may force or draw ambient air into the first condenser 158, such as
in a first direction 220, across the condenser coils 218 within the
housing 200, and out of the housing 200 in a second direction 222
away from the housing 200, the first condenser 158, and the second
condenser 162. The illustrated embodiment of FIG. 6 includes the
barrier 166 disposed between the first condenser 158 and the second
condenser 162, in which the barrier 166 blocks ambient air directed
by the plurality of fans 160 from flowing across the top panel 202
and/or the side panel 210. However, as discussed herein, in
alternative embodiments, the barrier 166 may be adjustable or may
be removed to enable the plurality of fans 160 to direct some air
across the top panel 202 and/or the side panel 210 and across the
second condenser 162. In further embodiments, a position of the
fans 160 may be adjusted to enable air to be directed across the
second condenser 162 via the fans 160.
[0061] FIG. 7 is a schematic of an embodiment of the second
condenser 162 coupled to a wall 250 of the HVAC system 150, such as
the top panel 202 and/or the side panel 210. The second condenser
162 includes a coil 252 that is disposed along a section of the
wall 250. In the illustrated embodiment, the coil 252 is disposed
in a zigzag or serpentine arrangement along a surface of the wall
250. The coil 252 includes a plurality of coil segments 254 that
are disposed adjacent to one another along a longitudinal length
256 of the wall 250, and each coil segment 254 extends
substantially parallel to one another along a lateral length 258 of
the wall 250. In some embodiments, each coil segment 254 may be
separated from an adjacent coil segment 254 by a distance 260. The
distance 260 may be set or selected to enable a desirable amount of
heat transfer between the refrigerant and the ambient environment
and may be between 25 millimeters (mm) and 75 mm. Additionally, the
coil 252 may have a total length of between 100 meters (m) and 150
m extending across the wall 250.
[0062] FIG. 8 is a schematic cross-sectional view of an embodiment
of the coil 252 coupled to the wall 250 having an exterior surface
270 that is exposed to an ambient environment 272. In some
embodiments, the coil 252 may be directly coupled to, or directly
in contact with, an interior surface 274 of the wall 250 to enable
heat to transfer from the refrigerant within the coil 252 to the
wall 250 via conduction. For example, grooves or recesses 276 may
be formed or machined into the interior surface 274. The groove 276
may receive the coil 252 and may be formed to match the shape of
the coil 252, such that the coil 252 is in contact with an
increased amount of the wall 250 to enable a greater amount of heat
transfer between the coil 252 and the wall 250. For example, the
coil 252 is at least partially surrounded by the interior surface
274 of the wall 250, thereby increasing an amount of surface area
of the coil 252 in contact with the wall 250. In the illustrated
embodiment, the coil 252 has a circular cross-sectional geometry
and may have a diameter 280 between 5 mm and 10 mm, and the groove
276 has a semicircular cross-sectional geometry to surround,
contact, and/or capture approximately 50% of the circumference of
the coil 252. However, in additional or alternative embodiments,
the coil 252 may have a different cross-sectional geometry, and the
groove 276 may have corresponding cross-sectional geometry to
receive and/or surround at least a portion of the perimeter of the
coil 252. Moreover, to enable greater heat transfer between the
wall 250 and the coil 252, the wall 250 and/or the coil 252 may be
formed from a metallic material, such as aluminum, steel, iron,
another suitable material, or any combination thereof.
[0063] In some embodiments, conductive tape 282 may be used to
couple and/or secure the coil 252 within the groove 276 of the wall
250. The conductive tape 282 may use adhesives to attach the coil
252 onto the interior surface 274 of the wall 250 and may
facilitate heat transfer from the coil 252 to the wall 250. As an
example, the conductive tape 282 may include a metallic or
otherwise conductive material, such as aluminum. In certain
embodiments, insulation 284 may be placed over the coil 252 and/or
the conductive tape 282 to block heat from transferring away from
the wall 250 to a remainder of the HVAC system 150, such as an
interior of the housing 200. For example, an interior partition
286, such as the barrier 166, may be positioned adjacent to the
wall 250, and insulation 284 may be positioned between the interior
partition 286 and the wall 250. The insulation 284 may also abut
and press the coil 252 against the wall 250 and further secure the
coil 252 onto the wall 250. As such, the insulation 284
substantially blocks heat from transferring from the coil 252
and/or the wall 250 to the interior partition 286. Furthermore, the
insulation 284 also blocks or restricts an air flow, such as the
air flow directed by the fan 160, from contacting the wall 250
and/or the coil 252. By way of example, the insulation 284 may be
formed from a polymeric material, such as polyurethane foam.
[0064] FIG. 9 is a schematic cross-sectional view of another
embodiment of the second condenser 162 positioned adjacent to the
interior surface 274 of the wall 250 having the exterior surface
270 exposed to the ambient environment 272. For example, the second
condenser 162 may be coupled to the insulation 284, and the
insulation 284 may be coupled to the interior surface 274 of the
wall 250. The insulation 284 of FIG. 9 may be made from the same or
a different material than the insulation 284 of FIG. 9. For
example, the insulation 284 of FIG. 9 may additionally or
alternatively include a conductive filler, mixture, or other added
material that may conduct thermal energy from the second condenser
162, through the insulation 284, and to the wall 250. That is, the
conductive filler of the insulation 284, such as metallic
particles, strips, tape, and/or another suitable filler, may
increase an amount of heat that may travel through the insulation
284. As such, the insulation 284 may enable a sufficient amount of
heat to transfer from the second condenser 162 to the wall 250 and
to the ambient environment 272, thereby cooling the refrigerant
flowing through the second condenser 162. In this manner, the
second condenser 162 may be thermally coupled to the wall 250.
[0065] In some embodiments, the second condenser 162 may include a
first header 320 and a second header 322. The refrigerant may enter
the second condenser 162 via the first header 320, may flow through
a plurality of conduits 324, which may each be similar to the coil
252, and may exit the second condenser 162 via the second header
322. Thus, the first header 320 may be fluidly coupled to the
compressor 156 that directs refrigerant to the second condenser
162, and the second header 322 may be fluidly coupled to the
expansion device 164 that receives the refrigerant from the second
condenser 162. In some embodiments, the conduits 324 may each be
channels, such that the second condenser 162 is a microchannel-type
heat exchanger. Additionally or alternatively, the conduits 324 may
each be tubes, and the second condenser 162 may be a shell and tube
type heat exchanger. As shown in FIG. 9, the second condenser 162
includes three conduits 324 that each extend approximately parallel
to one another and with respect to a longitudinal axis 328.
However, in additional or alternative embodiments, the second
condenser 162 may include any suitable number of conduits 324 that
extend in any suitable manner, such as in a serpentine pattern, as
described in FIG. 7. At least a portion of the conduits 324 may be
thermally coupled to the insulation 284. That is, heat may transfer
from the refrigerant, to the conduits 324, and to the insulation
284 toward the ambient environment 272.
[0066] Additionally, the second condenser 162 may include a
plurality of fins 326 that contact each conduit 324, such that heat
may transfer from the refrigerant to the conduits 324 and to the
fins 326. For example, each conduit 324 may extend through and be
in thermal communication with each fin 326. In additional or
alternative embodiments, each conduit 324 may extend through some
of the fins 326, but not all of the fins 326. Each fin 326 may also
be coupled to the insulation 284, such that heat may transfer from
the conduits 324, to the fins 326, and to the insulation 284 toward
the ambient environment 272. Thus, the fins 326 may further enable
heat transfer between the refrigerant and the ambient environment
272. Each fin 326 may be positioned cross-wise with respect to the
conduits 324, such as along a lateral axis 330 that is
perpendicular to the longitudinal axis 328.
[0067] In some embodiments, additional insulation may be disposed
between the second condenser 162 and an interior 332 of the HVAC
system 150. For example, the additional insulation may be
positioned between the second condenser 162 and the interior
partition 286 disposed within the interior 332 to block heat
transfer between the second condenser 162 and a remainder of the
HVAC system 150. The additional insulation may additionally or
alternatively block an air flow from contacting the second heat
exchanger 162, such as air directed by the fan 160.
[0068] FIG. 10 is a schematic of an embodiment of the second
condenser 162 having a fan 350 configured to direct air across the
second condenser 162. The fan 350 configured to direct air across
the second condenser 162 may be different than the fan 160
configured to direct air across the first condenser 158. For
example, the fan 350 may be configured to direct air across the
second condenser 162 but not the first condenser 158. In some
embodiments, the fan 350 may be configured to direct air generally
along the second condenser 162. That is, the fan 350 may direct air
in a direction 352 that is substantially parallel to the wall 250
of the embodiment of the second condenser 162 of FIGS. 7 and 8 or
parallel to the fins 326 of the embodiment of the second condenser
162 of FIG. 9. Operation of the fan 350 may increase the rate that
heat is removed from the refrigerant via forced convection. In some
embodiments, the fan 350 may be a variable speed fan, whereby the
rate at which the fan 350 directs air across the second condenser
162 may be adjustable. For example, the speed of the fan 350 may
increase to increase the rate that heat is removed from the
refrigerant, and vice versa. Although FIG. 10 illustrates one fan
350 configured to direct air across the second condenser 162, in
additional or alternative embodiments, there may be multiple fans
350 configured to direct air across the second condenser 162. Each
fan 350 may be independently controllable, such that the speed of
each fan 350 may be adjusted to direct air across the second
condenser 162.
[0069] The present disclosure may provide one or more technical
effects useful in the operation of an HVAC system. For example, the
HVAC system may cool a supply air flow by placing the supply air
flow in a heat exchange relationship with a refrigerant directed
through the HVAC system. The HVAC system may include a first heat
exchanger configured to cool the refrigerant and place the
refrigerant in condition to cool the supply air flow. For example,
the HVAC system may utilize a fan that directs air across the first
heat exchanger, such as a condenser, to cool the refrigerant
flowing through the first heat exchanger. The HVAC system may also
include a second heat exchanger, or an auxiliary heat exchanger, to
provide further and/or alternative cooling of the refrigerant. The
second heat exchanger may place the refrigerant in a heat exchange
relationship with ambient air to enable heat to transfer between
the refrigerant and ambient air without a mechanical component,
such as an additional fan. Including the second heat exchanger may
enhance a performance, such as an efficiency, of the HVAC system by
increasing a cooling capacity of the refrigerant with a relatively
small amount of additional energy consumption by the HVAC system.
In some cases, the refrigerant may be sufficiently cooled via the
second heat exchanger, such that the operation of the fan directing
air across the first heat exchanger may be reduced. As such, energy
consumption to operate the HVAC system is also reduced. The
technical effects and technical problems in the specification are
examples and are not limiting. It should be noted that the
embodiments described in the specification may have other technical
effects and can solve other technical problems.
[0070] While only certain features and embodiments of the
disclosure have been illustrated and described, many modifications
and changes may occur to those skilled in the art, such as
variations in sizes, dimensions, structures, shapes and proportions
of the various elements, values of parameters, including
temperatures and pressures, mounting arrangements, use of
materials, colors, orientations, and so forth without materially
departing from the novel teachings and advantages of the subject
matter recited in the claims. The order or sequence of any process
or method steps may be varied or re-sequenced according to
alternative embodiments. It is, therefore, to be understood that
the appended claims are intended to cover all such modifications
and changes as fall within the true spirit of the disclosure.
Furthermore, in an effort to provide a concise description of the
exemplary embodiments, all features of an actual implementation may
not have been described, such as those unrelated to the presently
contemplated best mode of carrying out the disclosure, or those
unrelated to enabling the claimed disclosure. It should be
appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation specific decisions may be made. Such a development
effort might be complex and time consuming, but would nevertheless
be a routine undertaking of design, fabrication, and manufacture
for those of ordinary skill having the benefit of this disclosure,
without undue experimentation.
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